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TXS0108E: Can TXS0108E push-pull support 100MHz SDIO ?

Terry Wu
Expert 1680 points
Part Number: TXS0108E
Other Parts Discussed in Thread: LSF0108

Hello Sirs,

I am so confused since datasheet show TXS0108 support 100MHz but I can't see use case from datasheet .

Now we need to support SDIO 3.0 100MHz for 1.8V<->3.3V push-pll I/O .

Datasheet description is 60MHz only.

May I know what's condition for TXS0108E support 100MHz ? Is it ok for SDIO 3.0 ?

Many thanks !

  • 0
    TI__Guru* 97046 points
    Hi Terry,
    In the TXS0108E datasheet, it lists the maximum data rate as 110 Mbps, which is not the same thing as 110 MHz. This would be equivalent to a 55 MHz square wave.

    For a 100 MHz signal (200 Mbps), I would recommend switching to LSF0108. This device has some limitations -- you will need a strong driver on both ends of the communication (preferably able to drive ~15mA), and the parasitic trace capacitance needs to be minimized on the 3.3V side. The total capacitive load to the 3.3V side of the LSF0108 should be kept below 6pF.

    High side pull-up resistors should be 330 ohm, and low side pull-up resistors should be 10 kohm.
  • 0 in reply to Emrys Maier
    Expert 1680 points

    Hello Maier,

    Many thanks your kindly reply !  Yes ! 110Mbps around 55MHz .

    For TXS0108, will it follow LSF0108 to close to 3.3V  , keep below 6 pf and have ~15mA driving capability for both end ?

    TKS !

  • 0 in reply to Terry Wu
    TI__Guru* 97046 points
    The amount of current drive required for TXS0108E is significantly lower than with the LSF0108 (~1mA), and the load can be significantly larger -- however a smaller load is better to improve signal integrity.

    I'm a bit confused by your posts - at first you wanted 100MHz, now it sounds like you're ok with 55MHz?